as far as algae goes , I think your tank is still going through the uglies and unfortunately it does affect coral. To combat this I would be buying more hermits / snails to hopefully eat algae off corals. I’ve learned nems go where they please, you could move him again only for it to go to the exact same spot lol , maybe just let it be and continue to monitor parameters / let your tank become more mature. I’ve moved my purple LTA like 5 times to the center and it has moved every time back to this spot on the side I’ve given up on moving it